This invention is an improvement on the invention shown in U.S. Pat. No. 4,948,611 which is incorporated herein by reference. While the invention shown in the patent was a substantial advance in the technology, there still existed occasional problems relating to bun spotting and blistering on the bun surface. Usually these problems relate to dough products that are left to rise in the pan with no forming or rolling processes after running through a sheeter roller or head roller. It is unclear exactly what causes these problems.
The new manifold and valving arrangement of this invention has served to substantially improve the previous arrangement as it reduces the internal pressure placed upon the dough and has improved the surface area to volume ratio. It is believed that higher pressures have a detrimental effect on the cellular structure and/or the longevity of the yeast in the dough product. Also the higher pressures are almost always accompanied by undesirable heat buildup. Preferably, the new arrangement uses a cut-off block with diameters permitting a product volume ratio (length to width) as extruded through the block prior to cut off close to a ratio of 1:1. While it is important that the pressure within the manifold be decreased, it is also important that the pressure be maintained above a minimum amount to avoid a phenomenon that allows the flow of the product to become unstable and create scaling problems. When the minimum pressure is maintained within the manifold accurate scaling is easily obtained.
The dough products that are normally run through the manifold are typically 40 to 45% moisture. The moisture contained within the product is held in the protein cell structure of the gluten forming "pockets" of water. The product must be handled carefully to avoid damaging the outer pockets of water. If the outer pockets are damaged, water is released and collects on the outside surface of the dough. The water collecting on the outside of the product will tend to make the product sticky and difficult to "machine" Effects of this situation are evident at the cut off knife, at the rounding bars and after the product is baked. Rupturing the water pockets may be caused by friction along the inside surface of the extrusion equipment. In a situation where there is a long narrow tube in which the product must flow, there is more volume of product which actually touches the wall of the tubing- The ratio between the total surface area of the conduit or pipe as compared to the total volume of the inside of the conduit is a quantitative measure of the percent of cellular rupturing occurring in the product. By decreasing the total surface area to the total volume of the vessel, the percentage of ruptured cells in the products will also be decreased proportionately. This decrease in cellular rupturing will increase the machinability of the product thereby decreasing the need for downstream efforts such as air bars and blower hoods. Also there is a decrease in the sensitivity of the rounder bar machine, less leakage at the rounder bars and a more consistent baked product. The manifold of this invention yields a much lower surface area to manifold area ratio then the previous tube-style manifold.